That depends on climate. The longer and colder your winters are, the more you benefit from the reliable efficiency of a ground source. Ground source heat pumps have been the most common choice for heating new single-family homes in Finland for the last ~20 years.

Yeah, not worth it in most cases, but when things line up, it is the best.

I've built 3 houses and got a bid on ground source heat for each one. I finally pulled the trigger on the 3rd house because we:

1) Moved where it was quite a bit colder, -20F for a week is common. 2) We have enough land to trench only 6'/2m deep to bury the loops instead of drilling like we would have needed to do on the first 2 houses. 3) There was a tax credit on it 4) No equipment exposed outside

Absolutely love it and it will make it difficult to move away when we want to down size b/c we'll pay more in utilities for half the space.

We also have some air-source on an addition I built, I'd use it anywhere that was slightly warmer than where I'm at.

Yeah, recently saw some numbers for air-to-air vs air-to-groundwater, and it break even after more than 25 years, with more than twice the initial cost

Bingo. Literally abandonded in Lithuania, air to air is so much cheaper. Some builders even ditch hp altogheter - basic electric underfloor heating + solar panels is so much cheaper.

I'm in New Zealand and my bedroom heater is $20 electric + $20 smart plug + $10 temperature sensor. Winter bill is ~$100 NZD. It would take ~20 years for heat pump to recover install cost alone.

To jakozaur’s point, there’s plenty of reasons drilling can get cheaper and there’s at least one other company working on it [1]—would love to hear about others! I’m a minimally informed amateur but my intuition is that the way it’s typically done (multiple inch borehole, U-tube geometry) is fairly suboptimal since the diameter is a lot wider than you need it to be just for hydrodynamic resistance and you get losses from the outgoing liquid cooling the incoming liquid. Dropping the diameter should make drilling a lot easier—-you can sink a 5/8”x12’ ground rod with hand tools in the right soil! (you’d still have to figure out how to make the holes meet up but I imagine there are ways of doing this).

[1] https://www.borobotics.ch/

[dead]

You might still get the most out of it when the AMOC collapses.

The challenge is for people who live in apartment buildings in urban environment where you have no front yard you can drill into at your leisure.

Does the ground source heat up (or cool down) over time, making it less effective? The deep ground is very well insulated, which is why after a century of operation the London Underground is 10 degrees warmer. I wonder whether GSHP users need to balance their load by (say) consuming more heating than they actually need in winter so that summer cooling remains effective.

Out of curiosity, has the demand stayed the same? I'm asking because you see the same with electricity grids, designed in a different time with much lower demand.

Sorry to hear this, it seems like a great system to me but you have to have the capacity right. I'm planning on getting one in the next year but the drilling will be more than we need and we opt for no glycol (yet) as that also gives us headroom

If you're an individual with an apartment you don't have the choice to drill.

If you're building the apartment building you have the choice to drill for the entire building, and the number of units that benefit mean this is much more cost efficient than with single family homes.

In sensible countries each housing unit have a central heating solution, regardless of where the heat comes from.